In the last few years, there has been considerable interest in "soft-serve" ice cream, yoghurt and various non-dairy frozen confections, that are custom flavored by individual servings. There are some machines on the field, that will mix and soften a "hard-scooped" product. Frequently the mixing and softening is done by hand, on a board with a spatula. The available machines fall into two categories: one type is a screw extruder, it utilizes a conical screw, and a matching conical cup with an orifice at its apex. This machine extrudes the product onto a cone or dish. Although this machine has been on the market for decades, and can produce an excellent product, it did not become universally accepted for various reasons. The other type of machine, is more recent; it is a heavy duty high speed spinner-mixer. It produces a semi-liquid product to be served in a cup with a spoon.
The subject invention utilizes a piston and cylinder for pressurizing the product for extrusion, a special rotating wheel on a retractable shaft to mix, cut, and sweep the aggregates into an extrusion orifice. This invention is related to a device described in my U.S. Pat. No. 4,668,561 titled "Confection Mixing Chopping and Extruding Apparatus", dated May 26 1987. The preferred embodiment of the subject invention is considerably more efficient in handling "hard" aggregate additions, it is more reliable in operation, it is considerably smaller and lighter in weight, and its manufacturing cost is only slightly higher than that of the preferred embodiment of said prior patent.
The state of the art frozen confection screw extruders require 1/2 to 3/4 horse-power motors to operate, while the subject device requires 1/10 to 1/20 horse-power input, for a similar capacity 3 inch diameter loading cup. Although this process takes a few seconds longer to accomplish, it resulted in a significantly less critical operation, since it is relatively easy to liquify a frozen confection by rapid "over-agitation". Ideally every part of the confection charge should receive the same amount of energy addition by agitation. In screw extruders, operating in the batch mode, the "tail end" of the product gets more agitation than the "front end", hence there is a tendency to over-soften the "tail end" of the product. The subject piston and cylinder mixer device, tends to soften the product uniformly, since it agitates only a small fraction of the total charge at a time, for equal time periods.